This invention is related to an improved lube oil. More specifically, the present invention is directed to a turbo oil having improved resistance to sea water corrosion.
In the past the corrosion resistant turbo oils which were used for jet engines in storage were not suitable for flying service because of excessive deposit formation. Because of this, the oil used during storage and transit had to be drained and replaced by a flying service type turbo oil before flight. This results in additional servicing of aircraft prior to initial flight, thereby increasing the cost and time to prepare the aircraft. In addition, stocks of both corrosion resistant storage/transit oil and turbo oil suitable for flying service have had to be maintained.
Work previously has been done to provide hydraulic and lubricating oil compositions which prevent corrosion of metal surfaces exposed to sea water. U.S. Pat. No. 3,872,048 discloses the use of the reaction product of an alkylated succinic anhydride, a polyethylene amine and a polyhydric alcohol. However, this composition would not be suitable for storage and operational use in turbine engines, since the composition tends to form deposits and is poor in oxidation stability.
U.S. Pat. No. 4,156,655 discloses a grease having improved resistance to salt water corrosion which has a metal naphthenate, preferably a zinc naphthenate, present. While this grease may be resistant to salt water corrosion, the corresponding lube oil with the disclosed additives would not be satisfactory as a turbo lube oil because a turbo lube oil having only zinc naphthenate present would not pass the standard salt water corrosion test, ASTM test D-665.
U.S. Pat. No. 3,684,726 also discloses the use of naphthenates of lead, zinc and lithium in greases for improved salt water corrosion resistance. While this patent discloses the use of metal naphthenates, there is no disclosure or suggestion of using the presently claimed combination of additives in a lube oil basestock to provide an improved turbo lube oil.
U.K. Pat. No. 1,117,349 discloses a gasoline additive useful in preventing carburetor icing and rusting comprising, in part, the reaction product of polyisobutylene succinic anhydride, tetraethylene pentamine and the ammonium salt of a phosphate ester. This patent also does not suggest or disclose the use of all of the presently claimed components in a turbo lube oil suitable for storage and also for operational use.
Accordingly, it would be desirable to provide a sea water resistant turbo oil which also is suitable for fly-away service.
It also would be desirable to provide a turbo oil for jet engines which does not require drainage and replacement prior to initial use of the engine.
The present invention is directed at a turbo oil comprising:
an ethoxylated alkylphenol; PA1 a zinc salicylate; PA1 a polyisobutylene-succinic acid/amine reaction product; PA1 mono- and dihexyl phosphate salts of C.sub.11 -C.sub.14 mono-amines; PA1 zinc naphthenate; and PA1 basestock. PA1 A. a basestock; PA1 B. an alkylphenol; PA1 C. a salicylate salt; PA1 D. a polyisobutylene-succinic acid/amine reaction product; PA1 E. a phosphate salt; and PA1 F. a naphthenate. PA1 A. tricresylphosphate; PA1 B. dioctyldiphenylamine; PA1 C. octylphenyl .alpha.-naphthylamine; PA1 D. n-octylphenothiazine; and PA1 E. 1,4-dihydroxyanthraquinone.